Re: [ARSCLIST] Optical Groove Digitization

["joe@xxxxxxxxxxx" <sergei01@xxxxxxxxxxxxx>]

When was the 15 degree cutting angle adopted?

Joe Salerno
Video Works! Is it working for you?
PO Box 273405 - Houston TX 77277-3405
http://joe.salerno.com
----- Original Message -----
From: "Steven Smolian" <smolians@xxxxxxxxx>
To: <ARSCLIST@xxxxxxxxxxxx>
Sent: Friday, September 26, 2003 8:59 PM
Subject: Re: [ARSCLIST] Optical Groove Digitization


> It's not just anti-skating.
>
> Every cartridge is designed to swing from left-to-right and back to the
> excursion required by a stereo record.  A three mill groove requires the
> cantalever to swing six times as far in both directions from the same
pivot
> point.
>
> The weight of the diamond is greater.
>
> The amount of downward force is greater by approximately 2-1/2 times to
keep
> the stylus from being thrown out of the groove.
>
> The cutting angle of 78s was 0 degrees, that of LPs, 15 degrees.
>
> The problem may not be anti-skate.
>
> Steven Smolian
>
> ----- Original Message -----
> From: "Rob Spencer" <rspencer11@xxxxxxxxxxx>
> To: <ARSCLIST@xxxxxxxxxxxx>
> Sent: Friday, September 26, 2003 2:53 PM
> Subject: Re: [ARSCLIST] Optical Groove Digitization
>
>
> > Duane Goldman wrote,
> >
> >  > As an eternal devil's advocate I still ponder the concept of
> >  > translating a continuous 3-D analog signal into a digital
> >  > representation . . . many educated ears are not satisfied with
> >  > digital reproduction. . . Perhaps in concert with such efforts
> >  > {at 3-D scanning] should be an equal expenditure to improve
> >  > analog recording & reproduction if for no other reason as to
> >  > establish a proper base point.
> >
> > As always, Dr. Goldman brings up points worth pondering, especially as
> > regards the reproduction of coarse-grooved records.  Wouldn't it be nice
> > to have a turntable/arm combination specifically engineered for 78
> > playback, as opposed to microgroove?  With proper anti-skating, at
least?
> >
> > More interesting is the question of digitization of the signal.  It
> > seems to me that the process of producing a highly accurate 3-D digital
> > image of the surface of a record does not digitize the signal, merely
> > the physical analogue of the signal as represented by the groove on the
> > record.
> >
> > In fact, the signal need not be digitized at all with this process,
> > whether the virtual groove is tracked virtually or used to produce a new
> > copy of the record for traditional playback (both options have been
> > discussed on this list).  It can be kept in analog form.  One may argue
> > that digitizing the record surface perforce digitizes the signal, but if
> > the accuracy is high enough it seems to me that there would be no effect
> > on the signal itself.
> >
> > In any event, the typical pre-tape 78 was recorded direct to disk, ore
> > or less, so unless there is access to the original metal parts or an
> > intermediate form, the record itself is the lowest-generation copy
> > available, so we are faced with the necessity of tracing its groove in
> > one way or another.  In theory, the process discussed herein would seem
> > to allow the most accurate extraction possible of the information
> > represented by the groove.  At the least, it would allow the
> > reconstruction of a mint copy of any record that has a groove that is
> > pristine at some level all along its length.  This last consideration
> > alone is enough to justify it for me.
> >
> >
> >
> > Rob Spencer
>